The present invention relates to an engine operation controller for a hybrid electric automobile, and more particularly to an engine operation controller for a hybrid electric automobile, suitable for use with a route bus, etc.
From the viewpoint of environmental protection, idling stop vehicles (called also idle stop vehicles), in which operation of the engine is automatically stopped when the vehicle is stopped, have recently been put to practical use. The idling stop vehicles are now spreading among route buses with a diesel engine. If such an idling stop is utilized, exhaust gas can be reduced and fuel consumption can be enhanced.
On the other hand, hybrid electric automobiles, in which an internal combustion engine and a motor are combined to obtain driving force, have hitherto been developed and put to practical use. The hybrid electric automobiles include a series hybrid electric automobile, which employs an engine as a power supply source for a motor, and a parallel hybrid electric automobile, in which the output shaft of an engine and the output shaft of a motor are both connected mechanically to a driving shaft.
The above-mentioned idling stop, incidentally, can be utilized in the hybrid electric automobiles. For example, when electric power for driving a motor is accumulated to more than a certain degree, operation of the engine is stopped if the speed of the vehicle is a predetermined speed or less, and the vehicle is driven only by the driving force of the motor.
However, in the case where the conventional idling stop technique and the conventional hybrid electric automobile technique are simply combined together, the following problems arise. For instance, in a vehicle such as a route bus that passengers get on and off, if the speed of the vehicle at which the engine is restarted is low, there are cases where operation of the engine is started immediately after the vehicle shifts from the stopped state to the traveling state. In such a case, some passengers at a stopping place may be given an unpleasant feeling by exhaust gas discharged by sudden starting of the engine. Note that if a speed at which the engine is restarted is set high, the above-mentioned problem can be eliminated. However, each time the vehicle is stopped at a traffic signal, etc., the stoppage time of the engine becomes long and therefore the amount of charge in the battery is reduced. As a result, the traveling performance may be lowered.
The present invention has been made in view of the problems mentioned above. Accordingly, it is an object of the present invention to provide an engine operation controller for a hybrid electric automobile that is capable of avoiding the situation in which passengers are given an unpleasant feeling by the engine restarted at a stopping place and in which passengers are frightened by engine-starting noise, when the idling stop technique is applied to a hybrid electric automobile. Another object of the present invention is to provide an engine operation controller for a hybrid electric automobile which is capable of assuring the amount of charge of the battery.
To achieve the objects of the present invention mentioned above, there is provided a first engine operation controller for a hybrid electric automobile equipped at least with a motor and an engine, comprising: speed detection means for detecting speed of the vehicle; control means for controlling operation of the engine; and decision means for deciding whether or not a stop of the vehicle is a stop at a stopping place;
wherein, if it is detected by the speed detection means that the speed is less than a predetermined value, operation of the engine is prohibited by the control means; and
delay means is provided for delaying removal of the operation prohibition of the engine when it is decided by the decision means that the stop of the vehicle is a stop at a stopping place.
Therefore, according to the first engine operation controller of the present invention, when a stop of the vehicle is a stop at a stopping place, the removal of the operation prohibition of the engine is delayed, compared with the case where the vehicle is standing at a traffic signal, etc. As a result, the present invention is capable of avoiding the situation in which passengers at a bus stop are exposed to exhaust gas and are frightened by engine-starting noise, while assuring the amount of charge of the battery. On the other hand, when a stop of the vehicle is not a stop at a stopping place, the operation prohibition of the engine is removed at relatively short timing and therefore a reduction in the amount of charge of the battery is prevented.
The first engine operation controller of the present invention may further comprise door detection means for detecting an open or closed state of a door of the vehicle. In this case, when an open or closed state of the door is detected by the door detection means, the decision means decides that the stop of the vehicle is a stop at a stopping place, and the removal of the operation prohibition of the engine is delayed.
With this construction, the stop of the vehicle at a stopping place is suitably decided. Therefore, when the vehicle is standing at a stopping place, the situation is avoided in which passengers at the stopping place are exposed to exhaust gas and are frightened by engine-starting noise. On the other hand, when an open or closed state of the door is not detected by the door detection means, it is decided that the stop of the vehicle is not a stop at a stopping place, and the operation prohibition of the engine is removed at relatively short timing. As a result, a reduction in the amount of charge of the battery is prevented.
In accordance with the present invention, there is provided a second engine operation controller for a hybrid electric automobile equipped at least with a motor and an engine, comprising: speed detection means for detecting speed of the vehicle; door detection means for detecting an open or closed state of a door of the vehicle; and control means for controlling operation of the engine;
wherein, if it is detected by the speed detection means that the speed is less than a first predetermined value, operation of the engine is prohibited by the control means;
thereafter, when an open or closed state of the door is not detected by the door detection means, the operation prohibition of the engine is removed by the control means if the speed becomes equal to or greater than a second predetermined value which is greater than the first predetermined value; and
when an open or closed state of the door is detected by the door detection means, the operation prohibition of the engine is removed by the control means if the speed becomes equal to or greater than a third predetermined value which is greater than the second predetermined value.
Therefore, when the speed of the vehicle becomes less than the first predetermined value and the engine is stopped, and then the door is not opened or closed, the operation inhibition of the engine is removed at relatively short timing. As a result, a reduction in the amount of charge of the battery is prevented. When an open or closed state of the door is detected after the stop of the vehicle, the operation prohibition of the engine is held until the speed of the vehicle becomes equal to or greater than the third predetermined value which is greater than the second predetermined value. Therefore, even when it takes time to get on and off, the present invention is capable of avoiding the situation in which, when the vehicle is started, the engine is restarted at a bus stop and passengers are exposed to exhaust gas and are frightened by engine-starting noise.
In accordance with the present invention, there is provided a third engine operation controller for a hybrid electric automobile equipped at least with a motor and an engine, comprising: speed detection means for detecting speed of the vehicle; door detection means for detecting an open or closed state of a door of the vehicle; and control means for controlling operation of the engine;
wherein, if it is detected by the speed detection means that the speed is less than a first predetermined value, operation of the engine is prohibited by the control means;
thereafter, when an open or closed state of the door is not detected by the door detection means, the operation prohibition of the engine is removed by the control means if a first predetermined time elapses; and
when an open or closed state of the door is detected by the door detection means, the operation prohibition of the engine is removed by the control means if a second predetermined time greater than the first predetermined time elapses.
Therefore, when the speed of the vehicle becomes less than the first predetermined value and the engine is stopped, and then the door is not opened or closed, the operation inhibition of the engine is removed, if the first predetermined time that is relatively short elapses after the stop of the engine. The first predetermined time is set to an average time during which a vehicle is standing at a traffic signal. Therefore, after the vehicle is started, restarting of the engine is permitted at relatively short timing. As a result, a reduction in the amount of charge of the battery is prevented.
On the other hand, when the speed of the vehicle becomes less than the first predetermined value and the vehicle is stopped, and then an open or closed state of the door is detected, the operation prohibition of the engine is removed when the second predetermined time greater than the first predetermined time elapses. In this manner, restarting of the engine is permitted. In the case where the vehicle is a route bus, the second predetermined time is set to an average time needed for the vehicle to move away enough from a bus stop after passengers get on and off at the bus stop. Therefore, the present invention is capable of avoiding the situation in which, when the vehicle is started, the engine is restarted at a bus stop and passengers are exposed to exhaust gas and are frightened by engine-starting noise.
In accordance with the present invention, there is provided a fourth engine operation controller for a hybrid electric automobile equipped at least with a motor and an engine, comprising: speed detection means for detecting speed of the vehicle; door detection means for detecting an open or closed state of a door of the vehicle; and control means for controlling operation of the engine;
wherein, if it is detected by the speed detection means that the speed is less than a first predetermined value, operation of the engine is prohibited by the control means;
thereafter, when an open or closed state of the door is not detected by the door detection means, the operation prohibition of the engine is removed by the control means, if a first predetermined time elapses and, in addition, the speed becomes equal to or greater than a second predetermined value which is greater than the first predetermined value; and
when an open or closed state of the door is detected by the door detection means, the operation prohibition of the engine is removed by the control means, if a second predetermined time greater than the first predetermined time elapses and, in addition, the speed becomes equal to or greater than a third predetermined value which is greater than the second predetermined value.
Therefore, when it is detected that the speed of the vehicle becomes less than the first predetermined value and, after the operation prohibition of the engine, an open or closed state of the door is not detected by the door detection means, the operation inhibition of the engine is held until the condition that the first predetermined time elapses, and the condition that the speed reaches the second predetermined value, are satisfied. Thereafter, if these conditions are satisfied, the operation prohibition of the engine is removed by the control means. Therefore, after the vehicle is started, restarting of the engine is permitted at relatively short timing. As a result, a reduction in the amount of charge of the battery is prevented. In addition, by providing the first predetermined time, the present invention is capable of preventing the repetition (hunting) of operation and stop of the engine 4 when the speed of the vehicle reaches the second predetermined value immediately after the speed becomes less than the first predetermined value, because of a traffic snarl, etc.
On the other hand, when the speed of the vehicle becomes less than the first predetermined value and operation of the engine is prohibited, and then an open or closed state of the door is detected by the door detection means, the operation prohibition of the engine is held until the condition that the second predetermined time greater the first predetermined time elapses, and the condition that the speed reaches the third predetermined value greater than the second predetermined value, are satisfied. Thereafter, if these conditions are satisfied, the operation prohibition of the engine is removed by the control means. In the case where the vehicle is a route bus, the second predetermined time is set to an average time needed for the vehicle to start after passengers get on and off at a bus stop. Therefore, the present invention is capable of avoiding the situation in which, when the vehicle is started, the engine is restarted at a bus stop and passengers are exposed to exhaust gas and are frightened by engine-starting noise. In addition, even if the second predetermined time elapses, restarting of the engine is prohibited until the speed of the vehicle becomes the third predetermined value or greater. Therefore, even if it takes time to get on and off, the present invention is capable of reliably avoiding the situation in which passengers are exposed to exhaust gas and are frightened by engine-starting noise.